EP0918618B1 - Soufflets de protection ameliores et procede de fabrication de ce type de soufflet de protection - Google Patents

Soufflets de protection ameliores et procede de fabrication de ce type de soufflet de protection Download PDF

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Publication number
EP0918618B1
EP0918618B1 EP97900517A EP97900517A EP0918618B1 EP 0918618 B1 EP0918618 B1 EP 0918618B1 EP 97900517 A EP97900517 A EP 97900517A EP 97900517 A EP97900517 A EP 97900517A EP 0918618 B1 EP0918618 B1 EP 0918618B1
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EP
European Patent Office
Prior art keywords
parison
core
product
mould
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP97900517A
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German (de)
English (en)
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EP0918618A1 (fr
Inventor
Changize Sadr
Jamie White
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Salflex Polymers Ltd
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Salflex Polymers Ltd
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Publication of EP0918618A1 publication Critical patent/EP0918618A1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/4242—Means for deforming the parison prior to the blowing operation
    • B29C49/4247—Means for deforming the parison prior to the blowing operation using spreading or extending means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/76—Neck calibration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/84—Shrouds, e.g. casings, covers; Sealing means specially adapted therefor
    • F16D3/843—Shrouds, e.g. casings, covers; Sealing means specially adapted therefor enclosed covers
    • F16D3/845—Shrouds, e.g. casings, covers; Sealing means specially adapted therefor enclosed covers allowing relative movement of joint parts due to the flexing of the cover
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
    • B29C49/04—Extrusion blow-moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/4242—Means for deforming the parison prior to the blowing operation
    • B29C49/4247—Means for deforming the parison prior to the blowing operation using spreading or extending means
    • B29C49/425—Means for deforming the parison prior to the blowing operation using spreading or extending means rods or bars entering the preform
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/703—Bellows
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/16—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
    • F16D3/20—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members
    • F16D3/202—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints
    • F16D3/205—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints the pins extending radially outwardly from the coupling part
    • F16D3/2055—Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members one coupling part having radially projecting pins, e.g. tripod joints the pins extending radially outwardly from the coupling part having three pins, i.e. true tripod joints

Definitions

  • This invention relates generally to blow molded, hollow articles of plastic material and methods of making such articles.
  • Blow molding is a well-known technique used for manufacturing hollow plastic articles such as bottles and the like.
  • a tube or "parison" of plastic material in a hot, moldable condition is positioned between two halves of a partible mold having a mold cavity of a shape appropriate to the required external shape of the article to be molded.
  • the mold halves are closed around the parison and pressurized air is introduced into the interior of the parison to cause it to expand and conform to the shape of the mold cavity.
  • the mold cools the plastic material to its final rigid shape and the mold is then opened and the article removed.
  • the parison is normally extruded through a die directly into position between the mold halves. This process is usually referred to as extrusion blow molding.
  • Articles such as bottles having relatively wide cylindrical body portions and narrower necks can be blow molded relatively easily.
  • difficulties are often encountered in blow molding articles having somewhat more unusual shapes.
  • An example of an article of this type is a protective bellows or boot which may be used to protect various automotive components such as rack and pinion steering systems, constant velocity joints and the like.
  • a relatively small diameter parison must be used.
  • bellows-like blow molded structures are for encapsulating automotive components whose alignment may change in use.
  • Typical examples are steering components such as rack and pinion steering systems as well as constant velocity joints commonly used in a power train, particularly in front wheel drive automobiles.
  • a constant velocity joint must permit the changes in angles which constantly occur as the vehicle travels down the road.
  • the joint is surrounded by a bellows-like boot.
  • the bellows serves to keep the desired lubrication in and dirt, salt and other foreign materials out of the joint.
  • a boot of this type includes a clamping surface at either end of the boot so that the boot may be attached to the shaft-like structures with a central bellows section providing the protective function as well as providing the necessary flexibility to the boot.
  • Boots of this type may be manufactured from a number of different materials.
  • One such material is rubber.
  • boots of this type have been manufactured from thermoplastic materials such as the thermoplastic resin identified under the trade mark HYTREL available from E.I. Dupont & Company.
  • HYTREL material is more desirable than rubber in that it appears to have superior flex fatigue, abrasion, low temperature start, vacuum collapse and high speed expansion characteristics as compared to rubber.
  • One area in which rubber boots exhibit superior performance is in dynamic impact to the boot when installed on a flexible joint.
  • boots of this type when manufactured from HYTREL may become prone to failure at the region where the skirt portion of the boot, made to accommodate one of the clamping means, merges into the bellows or flexible portion of the boot. It appears that the transition region between the internal support provided by the internal surface to which the boot is clamped and the region of the boot that no longer bears against metallic material is a location for failure.
  • blow molding techniques have not been satisfactory for manufacturing internal ribs whose configuration is not determined by the mold cavity itself.
  • the high pressure gas delivered internally of the molten parison pushes the parison out against the surface of the mold.
  • the interior surface of the parison typically is configured the same as the external surface and is smooth as the entire inner surface of the parison is subject to the air pressure of the blowing gas.
  • a pin is used to help deliver the necessary gas under pressure internally of the blow molded part.
  • a relatively small diameter parison may be extruded and then one end opened out by means of mechanical fingers or the like. After one end of the parison has been opened out, a core or mandrel may be inserted into the parison.
  • the core with its blow pin may extend the entire length of the parison and when the mold is closed there may be a tight fit between the blow pin of the core and the top of the mold to form a gas tight seal thereby permitting the gas pressure to build up inside the parison and perform the blow molding function.
  • the core is introduced into the large end of a stretched parison with the mold closed.
  • a further component of the mold often referred to as a slide is then closed against the core so that the dimension between the core and the closed slide then defines the second clamping surface.
  • the first clamping surface may be formed between the pin and the closed mold.
  • the process in accordance with this invention for manufacturing a product having a generally tubular configuration with first and second open ends which are generally axially aligned, said product having a bellows-shaped section and a skirt portion adjacent one of said first and second ends includes the steps of extruding a parison of blow moldable thermoplastic resin between portions of a partible mold, closing said mold around said parison, blow molding said bellows portion and compression molding said skirt portion.
  • a process for making a blow molded product in a mold which may be opened and closed comprises the steps of extruding a tubular thermoplastic resin parison which has first and second ends; closing the mold about the parison, introducing spreading means into the first end of the parison and spreading the first end of the parison to produce an enlarged opening at the first end, the parison having a wall thickness at the first end, supporting the parison at least adjacent the first end in the mold so that resin of the parison may not expand radially beyond the mold, introducing a core into the parison at the first end, the core having a portion with an outer surface adjacent the first end when the core is fully inserted which defines a clearance gap between the core and the closed mold.
  • the gap being less than the wall thickness of the parison at the first end so that upon introduction of the core, a portion of the thermoplastic resin comprising the parison is moved by the core and the core and the mold define a first end of the product, thereafter introducing a pressurized gas into the parison to blow mold the product.
  • a blow molded product has a generally hollow body portion with first and second open ends and the body portion having a flexible bellows-shaped portion intermediate the first and second ends, the first end comprises a skirt portion.
  • the skirt portion is defined by a generally cylindrical wall, the wall having inner and outer surfaces, the product having a transition section intermediate the bellows shaped portion and the skirt portion.
  • the transition section includes an internal rib to reinforce the bellows portion immediately adjacent the transition section.
  • a blow molded product has a generally hollow body portion with first and second open ends, the body portion having a flexible bellows-shaped portion intermediate the first and second ends, the first end comprising a skirt portion, the skirt portion being defined by a generally cylindrical wall, the wall having inner and outer surfaces.
  • the inner and outer surfaces of the skirt portion have different configuration.
  • the outer surface of the skirt is generally cylindrical and the inner surface comprises a plurality of discrete lobes projecting inwardly from the generally cylindrical wall.
  • FIG. 1 illustrates a boot in accordance with one aspect of the invention for use in a constant velocity joint.
  • the boot is shown generally at 10 and has first and second tubular ends 12 and 14.
  • a hose clamp will be attached externally of the end 12 and externally of the end 14.
  • the clamps will be tightened against the structure of the joint to form a tight seal so that lubricant contained within the boot 10 may not escape.
  • the joint will include two shaft-like elements, one having a diameter equal to the diameter of end 12 and the other having a diameter equal to end 14.
  • the boot 10 comprises a bellows-section 16 intermediate the first and second ends 12 and 14.
  • the flexible bellows section accommodates the relative angular movement of the structural portions of the constant velocity joint.
  • Figure 2 illustrates a prior art constant velocity joint boot similar to that in Figure 1.
  • the boot is shown generally at 20.
  • the boot 20 has a first end 22 and a second end 24.
  • the boot of Figure 2 would be clamped to the two elements of a constant velocity joint.
  • the boot 20 comprises a bellows section 26 for retaining the lubricant of the constant velocity joint.
  • FIG. 1 illustrates a portion of a constant velocity joint shown with respect to the left hand wall of the sections. In each case the joint bears the numeral 30.
  • the transition region between the bellows section 26 and the skirt 24 indicated generally by the arrow 32 in Figure 2 is a point of weakness in prior art boots. If the constant velocity joint, with its boot in place, is dropped or if another object is dropped onto the constant velocity joint with its boot or if a foreign object strikes the boot as the vehicle is driven and the area of impact is adjacent the area identified by arrow 32, the only material resisting the impact is the wall thickness of the boot 20 at that location. Because the boot 22 is made in conventional blow molding operations, the wall thickness of the boot 20 throughout the section 26 is relatively uniform. In order to provide greater resistance to failure at the location of arrow 32, it would be desirable to have additional material.
  • the extra material in the vicinity of arrow 42 is comprised of an internal rib 40.
  • the rib 40 extends circumferentially around the inner surface of the boot 10 and projects substantially radially inwardly at the transition between the end 14 and the bellows section 16.
  • the rib 40 is immediately adjacent the portion of the boot 10 that is shaped to its final configuration by the blow molding process.
  • the rib 40 thus provides considerable extra material in the region immediately adjacent the location of that portion of the constant velocity joint 30, thereby strengthening the boot 10 substantially as compared to the boot 20 of the prior art.
  • This improved boot provides improved impact resistance at the region of arrow 42 in a product where the bellows section 16 is manufactured in a blow molding process.
  • the process involves a typical blow mold illustrated generally at 50.
  • the mold 50 comprises partible mold halves 52 and 54.
  • the mold halves 52 and 54 are made up of a plurality of segments and these are shown as segments 52A, 52B, 52C, 52D, 52E, 52F, 52G and 52H and similar segments 54A through H.
  • the segments A through H of each of the mold halves are fixed to one another and move as a unit.
  • the mold halves 52 and 54 each comprise a moving slide 56 and 58 respectively.
  • the slides 56 and 58 may be moved independently of the sections 52A through H and 54A through H by means of cylinders 60 and 62.
  • the mold 50 is a conventional mold which may be used to manufacture boots of prior art configuration as well as the new boots of this invention.
  • the support pedestal comprises a movable core 72 which contains a movable blow pin 74.
  • the support pedestal also includes a cylinder 76 which moves the core 72 vertically relative to the support pedestal 70.
  • the support pedestal 70 also comprises a pair of fingers 78 which are movable relative to one another and to the pedestal 70 in the horizontal direction.
  • the support pedestal 70 is located vertically below an extrusion head which is not illustrated in the figures.
  • the mold halves when in the open position permit the extrusion of a parison 80 therebetween with the parison extending downwardly toward the support pedestal 70.
  • the mold halves 52 and 54 are in their open position.
  • the fingers 78 are drawn inwardly to their starting position.
  • the first step in the process is the extruding of the parison from the parison head.
  • the parison is relatively small in diameter and hangs vertically from the extrusion head.
  • the spacing of the fingers 78 is such that the parison drops over the fingers, the internal diameter of the parison is larger then the spacing between the fingers 78.
  • Figure 4 shows the second stage in the process. As shown in Figure 4, the fingers 78 have moved horizontally outwardly to create a relatively large diameter opening in the parison 80. The mold halves 52 and 54 have been closed to the final closed position and the slides 56 and 58 remain in the extended position.
  • Figure 5 shows the piston 76 having extended, moving the core 72 vertically upwardly between the fingers 78 and internally to the parison 80.
  • the core 72 stops in the position shown in Figure 5.
  • Figure 6 illustrates the next stage of the forming process.
  • the blow pin is extended vertically upwardly by means of a piston controlling relative movement between the blow pin 70 and the core 72.
  • the blow pin moves upwardly to engage the wall of the parison adjacent the upper segments 52A and 54A of the mold halves 52 and 54, sealing the parison at the top.
  • the interior of the parison is thus now sealed at both the first and second open ends.
  • Figure 7 shows the application of the blowing gas.
  • the parison is expanded outwardly against the mold 50 to complete the shaping of the boot.
  • This step is conventional and the techniques of blow molding conventionally used are applicable to this step.
  • Figure 8 shows the first stage of the retraction process. As shown in Figure 8 the blow pin retracts within the core 72 after the blow pressure is released.
  • Figure 9 shows the first stages of the mold opening.
  • the slides 56 and 58 respectively are moved to the retracted position. Moving the slides to the retracted position means that the outer surface of the parison adjacent the core 72 is no longer confined. After the slides have been retracted, the core 72 is withdrawn into the support structure 70 by collapsing of cylinder 76.
  • the slides 56 and 58 are in the extended or closed position prior to vertical upward movement of the core 72.
  • the fingers 78 hold the parison open read for entry of the core 72 within the parison.
  • the wall thickness of the parison adjacent the slides 56 and 58 will be established in the parison extrusion process.
  • the clearance between the slide 56 and the core 72 and between the slide 58 and the core 72 in each case, is less than the wall thickness of the parison 80 at that location. Accordingly, as the core 72 moves vertically upwardly, the core 72 forces movement of the thermoplastic material of the parison to permit entry of the core 72 into the mold 50.
  • the end 14 of the boot 10 comprises a skirt 82 having an external cylindrical surface 84.
  • the configuration of the external surface 84 of the skirt is determined by the configuration of the slides 56 and 58.
  • the internal configuration of the skirt 82, comprising the surface 86, is determined by the configuration of the core 72.
  • the wall thickness of the skirt 82 is determined around the periphery of the core 72 by the relative spacing horizontally between the core 72 and the slides 56 and 58 respectively.
  • the final configuration of the skirt 82 is defined by the space between the core 72 and the slides 56 and 58. Because the parison 80 has a wall thickness as extruded, greater than the thickness of the skirt 82, some thermoplastic material must be caused to flow out of the way as the core 72 enters the space between the slides 56 and 58. The material of the wall of the parison 80 is forced to flow and in this example is moved vertically upwardly. That material is free to run over the top of the parison forming a pool of thermoplastic material sitting on top of the core 72. That pool of material on top of the mandrel, when cooled, comprises the rib 40.
  • the configuration of the skirt 82 is thus completed in the step shown in Figure 5 before the blow pin moves into final position and before the blowing gas pressure is applied to the parison 80.
  • the skirt 82 receives its final configuration, not from the blow molding pressure but rather from a compression molding procedure.
  • the rib 40 is formed at the transition between the portion of the boot 10 which is compression molded, that is the skirt 82, and the portion of the boot 10 which is blow molded, that is, the bellows-like section 16.
  • blow molded product has an internal rib formed from the excess material left over from the compression molding procedure. That extra rib then provides a strengthened area for what is otherwise a blow molded part.
  • Figure 11 illustrates a boot which is similar to that shown in Figure 1 except that the larger diameter end 114 is considerably more complex than end 14 shown in Figure 1. The same steps as diagrammatically illustrated in Figures 3 through 10 would be used to manufacture the boot shown in Figure 11.
  • the boot 100 illustrated in Figure 11 comprises a relatively narrow end portion 112 and a relatively large diameter end 114.
  • the boot comprises a central bellows-like portion 116 intermediate the ends 112 and 114.
  • the boot 100 comprises a skirt 120 at the first end 114.
  • the skirt 120 has a substantially cylindrical outside surface 122.
  • the internal surface 124 of the skirt 120 is generally cylindrical but with three lobes 126 extending radially inwardly from the cylindrical surface 124.
  • the surface 124 comprises ribs 128 which extend radially inwardly from the surface 124.
  • the ribs 128 may extend entirely around the periphery of the surface 124 including around the internal surface of the lobes 126.
  • the skirt 120 also comprises a pair of horizontal grooves 132 located in the external surface 122 adjacent each of the lobes 126. These are shown more clearly in Figure 13. Finally, the skirt 120 may advantageously include three tabs 134 spaced about the periphery of the surface 122. These tabs extend radially outward from surface 122.
  • the boot 100 comprises a generally annular rib 136 adjacent a surface 138.
  • the surface 138 extends inwardly and upwardly from the skirt 120 toward the bellows-like portion 116.
  • the rib 136 is at the transition between the surface 138 and the bellows portion 116.
  • the boot shown in Figure 11 may be made using the process discussed in connection with Figures 3 through 10 by using the apparatus shown in Figure 12.
  • the apparatus of Figure 12 is essentially similar to that diagrammatically shown in Figure 3.
  • the mold 150 comprises mold halves 152 and 154.
  • the mold halves are segmented comprising sections 152A, B, C, D, E, F and G 154A, B, C, D, E, F and G.
  • the mold 150 also comprises slides 156 and 158 respectively.
  • the apparatus further includes a core 172 which is similar to core 72 shown in Figures 3 through 10.
  • the core 172 is supported in a support structure which is not illustrated but which operates essentially similar to that shown in Figure 3.
  • the slides 156 and 158 are movable horizontally under control of pistons 160 and 162 respectively.
  • the slide 158 includes a pair of horizontally inwardly directed plates 164.
  • the uppermost plate 164 is more clearly illustrated in Figure 14.
  • a top view of the core 172 is shown in Figure 15.
  • a parison 180 would be extruded to extend between the mold halves 152 and 154.
  • the mold halves would be closed and the core 172 moved into position as discussed in connection with Figures 3 through 10.
  • the parison material is not illustrated in order that the spacing between the core 172 and the mold 150 may be more clearly understood. Also, for the sake of clarity the surfaces of the mold which would be visible behind the plane of the section have not been illustrated.
  • the core 172 comprises a surface 182 which is adjacent the slides 156 and 158.
  • the core 172 further comprises a surface 184 which is adjacent the mold segments 152G and 154G.
  • this space represents the skirt 120 and the surface 138 of the boot 100 shown in Figure 11.
  • the surface 182 is generally cylindrical and defines what will become the surface 124 of the skirt 120.
  • the surface 182 defines the three lobes 126 as well as the ribs 128.
  • the ribs 128 illustrated in Figure 11 are formed by grooves 190 in the surface 182. Only a portion of the grooves 190 is shown opposite slide 156.
  • the small section indicated by the line 192 indicates a portion of the core 172 which has not been sectioned for the view of Figure 12.
  • the core 172 which has not been sectioned for the view of Figure 12.
  • the relieved areas or voids which form the lobes are shown in Figure 15. The voids are adjacent the surfaces 186.
  • the core 172 fits snugly against the edge 194 and the edge 196 of the slides 156 and 158 respectively.
  • the edges 194 and 196 are substantially semi-circular. Small voids in the slides 156 and 158 may be provided to define the tabs 134.
  • the tabs 134 may be useful in retaining the hose clamp in its desired position prior to tightening the clamp when the boot is being installed.
  • the surface 186 will help to form the lobe 126.
  • the grooves 132 are formed in the external surface of the skirt 120 by reason of the fingers 164.
  • the thermoplastic material that is captured between the core 172 and the slides 156 and 158 as well as the mold sections 152G and 154G is subjected to compression and may flow radially, axially and circumferentially in the space defined by these surfaces. This forms the ribs 128, the lobes 126 and the grooves 132. Any excess material forced out of the space then forms the rib 136 comprised of material which flows onto the top of the core 172.
  • the plates 164 form the grooves 132.
  • the grooves 132 are advantageous in that larger lobes 126 may be formed.
  • the lobes 126 and the ribs 128 must all be made from the material which comprises the wall thickness of the parison. There are practical limits as to how much material can be included in the parison. Accordingly, where larger lobes are required to define the internal surface 124, the lobes can be made, in part, hollow.
  • One effective way of making the lobes in part hollow is by use of the grooves 132. Alternatively, the lobes could be made hollow by pins projecting vertically upwardly from the surfaces 186. This would leave a void in the lobe 126. These voids are shown in Figure 1 as 200.
  • the bellows section 116 blowing gas may be introduced into the parison through slots 190 in the core 172.
  • the slides 156 and 168 are first retracted. This removes the plates 164 from the grooves 132 and also permits radial expansion of the skirt 120 as needed. The core 172 may then be withdrawn without damaging the ribs 128 or the lobes 126.
  • the plates 164 are fixed to the slides 156 and 158. Slides 156 and 158 are extended before the core 172 is moved into place. Alternatively, plates similar to plates 164 could be mounted on additional slides or could be constructed as separately moveable parts of the slides 156, 158. In this case, the thermoplastic material would be forced under compression into the voids of the core creating the lobes 126 in a first stage. The additional slides or parts could then be moved into place to form the groove 132. This may be advantageous depending on the size and configuration of the lobes 126.
  • the narrower end 12 or 112 of the boot is formed by the space between the blow pin 74 and the mold sections 52A, 54A or the blow pin 174 and the mold sections 152A, 154A.
  • the ends 12 and 112 are thus each formed in a similar compression mold procedure to determine the final size and configuration of the smaller diameter ends of the boots 10 and 100 respectively. Any excess material from the parison is forced up and out the boot to be cut off as scrap.
  • the mold 50/150 and core 72/172 together with the blow pin 74/174 permit the compression molding of the first and second ends of the boots 10/100 and blow molding of the flexible portions 16/116.
  • the boot of Figure 11 thus provides a skirt which has a substantially cylindrical external configuration suitable for accepting a hose clamp.
  • the internal surface of the skirt 120 can be provided with a convoluted shape having one of more projections extending inwardly which are suitable for interacting with a non-cylindrical surface of the object to which the boot is to be clamped.
  • thermoplastic material capable of being used in a blow moulding operation including HYTREL may be used for the parison. Differing internal configuration as compared to the external configuration gives great flexibility to the design to strengthen blow moulded parts and to accommodate differing shapes in mating parts.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

L'invention concerne un produit moulé par soufflage. Ce produit présente généralement une forme tubulaire, et une première et une deuxième extrémités ouvertes (12, 14) ainsi qu'une section de soufflet (16) placé entre ces première et deuxième extrémités (12, 14), de telle sorte que le produit obtenu est flexible. Ce produit comporte également une jupe (82) adjacente à une des deux extrémités (12, 14). La section de soufflet (16) est formée au cours d'une opération de moulage par soufflage, et la section de jupe (82) est formée par moulage par compression. Un mode de réalisation préféré du produit comporte une nervure (40) qui s'étend à l'intérieur de la paroi de la section moulée par soufflage pour renforcer la zone de transition (42) entre la section de soufflet et la section de jupe (82) moulée par compression. Ce procédé comprend les étapes consistant à placer une paraison (80) dans un moule (50) et à introduire une partie centrale (74) dans la paraison (80) dans le moule. Cette partie centrale (74) déplace le matériau thermoplastique de manière axiale, et éventuellement, dans un sens radial et circonférentiel. Ce procédé permet de mouler un produit avec une surface externe qui peut être sensiblement cylindrique et dont la surface interne possède des lobes (126), des nervures (40, 128, 136) ou d'autres projections internes.

Claims (17)

  1. Procédé de réalisation d'un produit moulé par soufflage dans un moule (50, 150) qui peut être ouvert et fermé comprenant :
    a) l'extrusion d'une paraison de résine thermoplastique tubulaire (80, 180) comportant des première et seconde extrémités, ladite paraison (80, 180) comportant un axe général de symétrie et ladite paraison présentant une épaisseur de paroi au niveau de ladite seconde extrémité,
    b) la fermeture dudit moule (50, 150) autour de ladite paraison,
    c) l'introduction d'un moyen d'extension (78) dans ladite seconde extrémité de ladite paraison et l'extension de ladite seconde extrémité de ladite paraison tubulaire en vue de produire une ouverture élargie au niveau de ladite seconde extrémité,
    caractérisé par
    d) le support (56, 58, 156, 158) de ladite paraison (80, 180) au moins de façon adjacente à ladite seconde extrémité dudit moule (50, 150) de sorte que la résine de ladite paraison (80, 180) ne puisse pas s'étendre radialement,
    e) l'introduction d'un noyau (72, 172) dans ladite paraison (80, 180) au niveau de ladite seconde extrémité, ledit noyau comportant une partie présentant une surface extérieure (73, 182, 184, 186) adjacente à ladite seconde extrémité lorsque ledit noyau est totalement inséré, ce qui définit un interstice de jeu entre ledit moule fermé et ladite surface extérieure et ledit interstice de jeu est inférieur à l'épaisseur de paroi de ladite paraison au niveau de ladite seconde extrémité de sorte que, lors de l'introduction dudit noyau (72, 172), une partie de la résine thermoplastique constituant ladite paraison est déplacée par ledit noyau, et ledit noyau et ledit moule définissent une seconde extrémité dudit produit,
    et ensuite,
    f) l'introduction d'un gaz sous pression dans ladite paraison (80, 180) en vue de mouler par soufflage ledit produit.
  2. Procédé selon la revendication 1, dans lequel ledit moule (50, 150) comprend des coulisseaux de compression (56, 58, 156, 158) définissant la surface de moulage dudit moule de façon adjacente à ladite seconde extrémité dudit produit, et lesdits coulisseaux de compression sont déplacés vers la position étendue avant que ledit noyau (72, 172) ne soit introduit dans ladite paraison.
  3. Procédé selon la revendication 2, dans lequel ladite partie de ladite résine thermoplastique est déplacée dans une direction qui est sensiblement parallèle audit axe de ladite paraison.
  4. Procédé selon la revendication 3, dans lequel au moins une certaine quantité du matériau de résine qui est déplacé par ledit noyau comprend une saillie (40, 124, 126, 128, 136) sur la surface interne dudit produit moulé.
  5. Procédé selon la revendication 4, dans lequel ladite saillie est une nervure continue (40, 128, 136).
  6. Procédé selon la revendication 4, dans lequel ladite saillie est une nervure circonférentielle s'étendant autour de la surface interne moulée dudit produit (40, 128, 136).
  7. Procédé selon la revendication 2, dans lequel ladite partie de ladite résine thermoplastique est amenée à s'écouler dans une direction qui est sensiblement radiale à l'axe de ladite paraison.
  8. Procédé selon la revendication 2, dans lequel ladite partie de ladite résine thermoplastique est amenée à s'écouler sensiblement radialement et circonférentiellement par rapport audit axe.
  9. Procédé selon la revendication 7, dans lequel ledit noyau comprend au moins un vide sur une surface dudit noyau de façon adjacente audit moule de sorte que, lors de l'introduction dudit noyau dans ladite paraison, au moins une partie dudit matériau thermoplastique puisse s'écouler dans ledit au moins un vide.
  10. Procédé selon la revendication 2, dans lequel, après que ledit gaz sous pression soit introduit dans ladite paraison, lesdits coulisseaux de compression sont déplacés vers une position rétractée, et ensuite ledit noyau est enlevé de l'intérieur de ladite seconde extrémité dudit produit.
  11. Procédé selon la revendication 9, dans lequel ledit noyau comprend au moins un vide (186, 190) sur ladite surface extérieure dudit noyau en vue de définir au moins une saillie interne sur ledit produit, de sorte que, lors de l'introduction dudit noyau dans ladite paraison, une partie dudit matériau thermoplastique s'écoule dans ledit vide.
  12. Procédé selon la revendication 11, dans lequel ledit vide dans ledit noyau est une rainure annulaire (190) de sorte que ledit produit moulé comprend au moins une nervure (40) sur la surface interne dudit produit de façon adjacente à ladite seconde extrémité (14) dudit produit.
  13. Procédé selon la revendication 1, caractérisé en outre par l'introduction dudit noyau (72, 172) dans ladite seconde extrémité de ladite paraison (80, 180) de sorte que ledit noyau et ledit moule (50, 150) définissent les surfaces intérieure et extérieure dudit produit moulé de façon adjacente auxdites première et seconde extrémités.
  14. Procédé selon la revendication 7, ledit moule (50, 150) comportant des coulisseaux de compression supplémentaires (52a, 54a) adjacents à ladite première extrémité, ledit procédé comprenant le déplacement desdits coulisseaux de compression supplémentaires d'une position rétractée vers une position étendue après que ledit noyau ait été introduit dans ladite paraison.
  15. Procédé de fabrication d'un produit (10, 100) présentant une configuration sensiblement tubulaire comportant des première et seconde extrémités ouvertes qui sont alignées de façon sensiblement axiale, ledit produit présentant une section en forme de soufflet (36, 116) et une partie de jupe (14, 114) adjacente à ladite seconde extrémité, comprenant les étapes consistant à :
    a) extruder une paraison (80, 180) de résine thermoplastique pouvant être moulée par soufflage entre des parties d'un moule pouvant être séparé en deux de ladite paraison comportant des première et seconde extrémités,
    b) fermer ledit moule (50, 150) autour de ladite paraison,
    caractérisé par les étapes consistant à :
    c) introduire un noyau (72, 172) dans ladite seconde extrémité de ladite paraison en vue de mouler par compression ladite partie de jupe (14, 114) et,
    d) mouler par soufflage ladite partie de soufflet (16, 116).
  16. Procédé selon la revendication 15, dans lequel ledit moulage par compression est exécuté immédiatement avant ledit moulage par soufflage.
  17. Procédé selon la revendication 16, dans lequel ledit noyau (72, 172) est introduit dans ladite paraison (80, 180) en vue de mouler par compression lesdites première et seconde extrémités dudit produit (10, 100).
EP97900517A 1996-08-08 1997-01-21 Soufflets de protection ameliores et procede de fabrication de ce type de soufflet de protection Expired - Lifetime EP0918618B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US08/694,234 US5900205A (en) 1996-08-08 1996-08-08 Method for blow molding a CVJ boot
US694234 1996-08-08
PCT/CA1997/000037 WO1998006558A1 (fr) 1996-08-08 1997-01-21 Soufflets de protection ameliores et procede de fabrication de ce type de soufflet de protection

Publications (2)

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EP0918618A1 EP0918618A1 (fr) 1999-06-02
EP0918618B1 true EP0918618B1 (fr) 2001-04-11

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EP97900517A Expired - Lifetime EP0918618B1 (fr) 1996-08-08 1997-01-21 Soufflets de protection ameliores et procede de fabrication de ce type de soufflet de protection

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US (1) US5900205A (fr)
EP (1) EP0918618B1 (fr)
JP (1) JP3404403B2 (fr)
CA (1) CA2260032C (fr)
DE (1) DE69704563T2 (fr)
ES (1) ES2155986T3 (fr)
WO (1) WO1998006558A1 (fr)

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CN102328339B (zh) * 2011-09-27 2013-07-17 唐山市神州机械有限公司 一种加压成型***

Also Published As

Publication number Publication date
DE69704563D1 (de) 2001-05-17
JP3404403B2 (ja) 2003-05-06
EP0918618A1 (fr) 1999-06-02
DE69704563T2 (de) 2001-08-09
CA2260032A1 (fr) 1998-02-19
US5900205A (en) 1999-05-04
CA2260032C (fr) 2004-08-03
JP2000515827A (ja) 2000-11-28
ES2155986T3 (es) 2001-06-01
WO1998006558A1 (fr) 1998-02-19

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